Blossom End Rot

Blossom end rot is a common disorder that affects the fruit of many vegetables. While tomatoes are most often affected, peppers, eggplants, and even summer squash can also develop this problem.

What Is Blossom End Rot?

Blossom end rot appears as a sunken, leathery spot on the bottom (blossom end) of developing fruit. The affected area is typically dark brown or black.

Although it looks like a disease, blossom end rot is actually caused by a lack of calcium reaching the fruit.

Why It Happens

Calcium is essential for healthy fruit development, but plants cannot move calcium once it has been deposited in mature tissues. This means a constant supply is needed while fruit is forming.

• Rapid leaf and stem growth in spring can divert calcium away from fruit.
• Inconsistent watering during dry periods limits calcium uptake.
• Root disturbance can interfere with nutrient absorption.

When Blossom End Rot Is Most Common

This disorder is most common early in the season, when plants are growing rapidly and root systems are still developing. As growth slows and roots become established, many plants grow out of the problem.

What to Do When You See It

• Remove damaged fruit so the plant doesn’t waste energy.
• Water consistently, especially during hot or dry weather.
• Avoid excessive nitrogen fertilization, which promotes leaf growth over fruit development.

Long-Term Solutions

If blossom end rot continues throughout the season, a soil test is recommended to determine if calcium levels are low.

• Calcium may be added in the form of gypsum if soil tests indicate a deficiency.
• Use a fertilizer low in nitrogen and higher in phosphorus to encourage fruit development.
• Foliar calcium products, such as Ferti-lome Yield Booster, can supply calcium that plants can absorb directly through their tissues.

Helping Plants Recover

With consistent watering, proper fertilization, and good root development, most plants recover and produce healthy fruit for the remainder of the season.